Method for ashing

Abstract

The present invention provides an ashing method using rapid heat transfer under high pressure. The present method, applicable to all photoresist ashing processes, can rapidly remove hardened photoresists without popping at the ashing step by baking high dose ion implanted silicon substrate on a hot plate, enhancing the ashing quantity, by drastically reducing the ashing process time, while allowing conventional equipments to be used further. The present method comprises an in situ baking step, wherein a silicon substrate is baked for a predetermined time period under a pressure of 10 Torr or more while it is placed on a hot plate; a vacuumizing step, wherein a stable vacuum status is achieved while the silicon substrate is placed on the hot plate; a gas processing step, wherein selected reaction gas is introduced into a reaction chamber; and an ashing step, wherein plasma is generated until almost all of the photoresists are removed.

1 . An ashing method comprising: 
 an in situ baking step, wherein a silicon substrate is baked for a predetermined period of time under a pressure of 10 Torr or more while said silicon substrate is placed on a hot plate;    a vacuumizing step, wherein a stable vacuum status is achieved while said silicon substrate is placed on said hot plate;    a gas processing step, wherein selected reaction gas is introduced into a reaction chamber; and    an ashing step, wherein plasma is generated until almost all of the photoresists are removed.    
     
     
         2 . The ashing method as set forth in  claim 1 , wherein the temperature of said hot plate is from 200° C. through 300° C.  
     
     
         3 . The ashing method as set forth in  claim 2 , wherein the temperature of said hot plate is from 230° C. through 270° C.  
     
     
         4 . The ashing method as set forth in  claim 1 , wherein said predetermined period of time at said in situ baking step is longer than five seconds, but not longer than twenty seconds.  
     
     
         5 . The ashing method as set forth in  claim 1 , wherein said reaction gas comprises one or more of O 2 , N 2 , H 2 N 2 , O 3 , or CF 4 .  
     
     
         6 . The ashing method as set forth in  claim 1 , wherein said silicon substrate is dose ion implanted.  
     
     
         7 . The ashing method as set forth in  claim 1 , wherein said silicon substrate is a via-etched substrate.  
     
     
         8 . The ashing method as set forth in  claim 1 , wherein said silicon substrate is a pad-etched substrate.  
     
     
         9 . The ashing method as set forth in  claim 1 , comprising additionally an over-ashing step, in which plasma is continuously generated even after almost all of the photoresists have been removed by plasma generated at said ashing step.